The Oklahoma Court of Criminal Appeals agreed Monday to wait to set execution dates for two more death row inmates until a grand jury finishes its closed-door investigation into drug mix-ups during the state's last two lethal injections.

The court granted the stays for two convicted killers - Richard Stephen Fairchild and Jeremy Alan Williams - who have already exhausted all state and federal appeals of their convictions and death sentences. This brings to five the number of inmates whose executions have been put on hold while Oklahoma Attorney General Scott Pruitt's office continues to explore how the wrong drug was delivered for the state's last two executions.

The five-member court said it wouldn't be appropriate to set execution dates for Fairchild and Williams while the grand jury probe is ongoing.

Fairchild, 56, was sentenced to die for the 1993 beating death of his girlfriend's 3-year-old son in Del City. Williams, 32, was given the death penalty for killing a bank teller during a robbery of Tulsa's First Fidelity Bank in 2004.

The court already has issued stays of execution for three other death row inmates - Richard Glossip, Benjamin Cole and John Grant.

Glossip was just hours away from his scheduled lethal injection in September when prison officials realized they received potassium acetate instead of potassium chloride, the third drug in the state's execution protocol. Later, an autopsy report indicated the wrong drug was used in January 2015 to execute Charles Warner.

After that revelation, Pruitt launched a multicounty grand jury investigation into the state's execution protocol and what went wrong. The grand jury conducts its investigations in secret, but the former warden of Oklahoma State Penitentiary and the ex-director of the Department of Corrections both have appeared to testify. Both have since left the agency. Ex-warden Anita Trammell retired in October, and Patton resigned in December to take a job with a private prison company in Arizona.

When the grand jury concludes its investigation into the Department of Corrections' handling of its execution protocol, it will issue an interim report with its findings, said Pruitt spokesman Aaron Cooper. The grand jury also could issue indictments for criminal charges.

Pruitt has said he will not request any execution dates until at least 150 days after his investigation is complete, the results are made public and his office receives notice that the prisons department can comply with the state's execution protocol.